Transesterification using modified lipase

As discussed in section 3.6, the fatty acids in milk fat are not distributed randomly and the melting point may be modified by randomizing the fatty acid distribution by transesterification using a lipase or chemical catalysts. 

It was necessary to add over 10% buffer for the transesteiification of phosphatidyl choline by native lipase (5). Hydrolysis occurred as a side reaction in the hydrophobic solvent-water system. Tlie transesterification of phosphatidyl choline and eicosapentaenoic acid (EPA) was carried out in water-saturated n-hexane using palmitic acid-modified lipase. Table II shows the transesterification of phosphatidyl choline and EPA. Modified lipase made it possible for the transesterification of phospholipids in organic solvents. 

Pyromellitic dianhydride has been used to modify the amino groups of P. cepacia lipase which was then used in transesterification reactions in n-octane and DMF. The modified lipase gave initial reaction rates in DMF higher than unmodified pH-tuned lipase (that showed no activity at all under the same conditions) [32]. 

Mogi, K-I, Nakajima, M and Mukataka, S (2000) Transesterification reaction between medium- and long -chain fatty acid triglycerides using snrfactant-modified lipase. Biotechnol. 

In the food industry, lipases are used in lipid modification processes. In these processes the texture, digestibility, or physical properties of natural lipids are modified by lipase-catalyzed transesterification reactions with lipids other than the original fatty acids. In the baking industry, lipases are used to influence the quality of bread through modification of the wheat flour lipids. Finally lipases are used for flavor enhancement of cheese in the dairy industry. 

Catalysts speed up chemical reactions in which they do not actually enter. They are typically used in small quantities. Raney nickel is used as a catalyst in hydrogenation of oils and sodium methoxide (sodium methanoate) in the transesterification of fats. Acids are used as catalysts in the production of certain modified starches. Catalysts also include the enzymes used as food additives, such as amylase (El 100), proteases (El 101, for example papain, bromelain and ficin), glucose oxidase (El 102), invertase (E1103) and lipases (El 104). 

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